Feat: crash log (#7)

Merged #6
- crash log (db0e1be9a02f70927124f9f3563df5e9dee3a764)
- perf(watchdog): limit buffer size and optimize crash substring search (https://github.com/versenilvis/IRIS/pull/7/commits/7725434fedf8b32929dc0d71e1256fda13cfdfca)
- refactor(crash): use dynamic buffer for stack trace capture (https://github.com/versenilvis/IRIS/pull/7/commits/07809a4330a1236471e8dae0e83afd4323a4c83a)

root/root.go

@@ -1,8 +1,12 @@
 package root
 
 import (
+	"bytes"
+	"context"
+	"errors"
 	"fmt"
 	"os"
+	"os/exec"
 	"strconv"
 	"syscall"
 
@@ -14,6 +18,7 @@ import (
 	_ "github.com/versenilvis/iris/commands/runner"
 	_ "github.com/versenilvis/iris/commands/search"
 	_ "github.com/versenilvis/iris/commands/view"
+	"golang.org/x/term"
 )
 
 var (
@@ -23,6 +28,15 @@ var (
 		Long: `IRIS (a.k.a Intelligent Real-time Input Suggestion) is a shell auto-autocompletion tool.
 It works exactly like coding editor suggestion menu drop down.`,
 		Run: func(cmd *cobra.Command, args []string) {
+			defer func() {
+				if r := recover(); r != nil {
+					WriteCrashLog(r)
+					restoreTerminal()
+					printCrashNotice()
+					startRescueShell()
+					os.Exit(2)
+				}
+			}()
 			if pidStr := os.Getenv("IRIS_PID"); pidStr != "" {
 				if pid, err := strconv.Atoi(pidStr); err == nil && pid > 0 {
 					_ = syscall.Kill(pid, syscall.SIGUSR1)
@@ -49,13 +63,117 @@ func init() {
 	rootCmd.PersistentFlags().BoolVarP(&debugMode, "debug", "d", false, "enable debug logging to iris.log")
 }
 
-func debugLog(format string, a ...interface{}) {
+func debugLog(format string, a ...any) {
 	if debugLogger != nil {
 		_, _ = fmt.Fprintf(debugLogger, format+"\n", a...)
 	}
 }
 
-func Execute() {
+// runWatchdog spawns the watchdog parent process
+func runWatchdog() {
+	exe, err := os.Executable()
+	if err != nil {
+		runOriginal()
+		return
+	}
+
+	// save original terminal settings in parent process
+	watchdogOldState, errState := term.MakeRaw(int(os.Stdin.Fd()))
+	if errState == nil {
+		_ = term.Restore(int(os.Stdin.Fd()), watchdogOldState)
+	}
+
+	r, w, err := os.Pipe()
+	if err != nil {
+		runOriginal()
+		return
+	}
+
+	cmd := exec.CommandContext(context.Background(), exe, os.Args[1:]...)
+	cmd.Env = append(os.Environ(), "IRIS_IS_CHILD=true")
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = w
+
+	err = cmd.Start()
+	if err != nil {
+		runOriginal()
+		return
+	}
+
+	_ = w.Close()
+
+	// copy child stderr to both our buffer and the real stderr, filtering out panics
+	var stderrBuf bytes.Buffer
+	origStderr := os.Stderr
+	tempBuf := make([]byte, 1024)
+	suppress := false
+	for {
+		n, errRead := r.Read(tempBuf)
+		if n > 0 {
+			_, _ = stderrBuf.Write(tempBuf[:n])
+			if stderrBuf.Len() > 64*1024 {
+				// discard oldest bytes to avoid memory leak
+				over := stderrBuf.Len() - 64*1024
+				_ = stderrBuf.Next(over)
+			}
+			if !suppress {
+				currentContent := stderrBuf.Bytes()
+				searchStart := 0
+				if len(currentContent) > n+12 {
+					searchStart = len(currentContent) - (n + 12)
+				}
+				searchSlice := currentContent[searchStart:]
+				idxPanic := bytes.Index(searchSlice, []byte("panic:"))
+				idxFatal := bytes.Index(searchSlice, []byte("fatal error:"))
+				triggerIdx := -1
+				if idxPanic != -1 {
+					triggerIdx = searchStart + idxPanic
+				} else if idxFatal != -1 {
+					triggerIdx = searchStart + idxFatal
+				}
+
+				if triggerIdx != -1 {
+					suppress = true
+					printedLen := len(currentContent) - n
+					if triggerIdx > printedLen {
+						_, _ = origStderr.Write(currentContent[printedLen:triggerIdx])
+					}
+				} else {
+					_, _ = origStderr.Write(tempBuf[:n])
+				}
+			}
+		}
+		if errRead != nil {
+			break
+		}
+	}
+
+	// check if child exited abnormally or crashed
+	errWait := cmd.Wait()
+	if errWait != nil {
+		content := stderrBuf.Bytes()
+		if bytes.Contains(content, []byte("panic:")) || bytes.Contains(content, []byte("fatal error:")) {
+			WriteCrashLog(string(content))
+			// restore terminal state if watchdog saved it
+			if watchdogOldState != nil {
+				_ = term.Restore(int(os.Stdin.Fd()), watchdogOldState)
+			}
+			printCrashNotice()
+			startRescueShell()
+			os.Exit(2)
+		}
+
+		var exitErr *exec.ExitError
+		if errors.As(errWait, &exitErr) {
+			os.Exit(exitErr.ExitCode())
+		}
+		os.Exit(1)
+	}
+}
+
+// runOriginal runs the normal command execution
+func runOriginal() {
 	if os.Getenv("IRIS_RELOADED") == "true" {
 		fmt.Printf("\r\033[K\033[35m[IRIS] reloading...\033[0m\n")
 		_ = os.Unsetenv("IRIS_RELOADED")
@@ -66,3 +184,12 @@ func Execute() {
 		os.Exit(1)
 	}
 }
+
+func Execute() {
+	if os.Getenv("IRIS_IS_CHILD") != "true" {
+		runWatchdog()
+		return
+	}
+
+	runOriginal()
+}